High-Efficiency PbS Quantum Dots Infrared Solar Cells via Numerical Simulation and Experimental Optimization

Abstract

Low-bandgap lead sulfide quantum dots (PbS QDs) can efficiently harness the infrared (IR) light in the solar spectrum beyond 1100 nm, showing great application potential in the bottom subcells of tandem solar cells. However, achieving further efficiency improvements in PbS QDs IR solar cells still faces many challenges. In this work, the effects of the absorber layer thickness, the carrier mobility in the absorber layer, the defect density in the absorber layer and at the absorber/electron transfer layer (ETL) interface, and the doping density of the ETL and hole transfer layer (HTL) on the performance of PbS QDs (≈0.95 eV) IR solar cells are systematically investigated through SCAPS-1D simulation. A theoretical efficiency of 16.95% and 2.15% is calculated for PbS QDs IR solar cells under AM 1.5 and 1100 nm-filtered illumination, respectively. Based on the simulation results, the corresponding PbS QDs IR solar cells are fabricated with an efficiency of 11.53% under AM 1.5 illumination, a remarkable 1100 nm-filtered efficiency of 1.30%, and a high external quantum efficiency of 70.50% at 1290 nm. Hence, these findings will accelerate the optimization of the performance of PbS QDs IR solar cells approaching their theoretical efficiency limit.